OF THE COMPOUND LEAF. 



61 



number and opposite. It is unequally pinnate when the rachis bears 

 an odd terminal leaflet, and equally pinnate when there is no terminal 

 leaflet, and interruptedly pinnate when the leaflets are alternately large 

 and small (159, etc). 



288. The number of leaflets in the pinnate leaf varies from 

 thirty pairs and upwards (as in some acacias), down to three, when the 

 leaf is said to be ternatc or trifoliate; or two, becoming binate, or 

 finally even to one leaflet in the lemon. Such a leaf is theoretically 

 compound, on account of the leaflet (blade) being articulated to the 

 petiole. 



163 



162 

 Compound leaves. 



165 

 163, Erigenia bulbosa. 



162, Clematis. 163, Erigenia bulbosa. 164, Acacia. 165, Honey-locust. 



289. A bipinnate leaf (twice pinnate) is formed when the rachis 

 bears pinna; or secondary pinnate leaves, instead of leaflets, and tripin- 

 nate (thrice pinnate), when pinna) take the places of the leaflets of a 

 bipinnate leaf. When the division is still more complicated the leaf is 

 decompound. 



290. Transition leaves. Different degrees of division often exist in different 



parts of the same leaf, illustrating the gradual transition of leaves from simple to 



169 • 166 168 167 



167, Lemon. 168, Jeffersonia. 169, Potentilla anserina. 166, P. tridental*. 



